EP0700335B1 - Process for feeding material to be pressed to a filter press - Google Patents

Abstract

PCT No. PCT/CH95/00054 Sec. 371 Date Nov. 22, 1995 Sec. 102(e) Date Nov. 22, 1995 PCT Filed Mar. 13, 1995 PCT Pub. No. WO95/26265 PCT Pub. Date Oct. 5, 1995In supplying material for pressing (37) into the press chamber of a filter press for separating solids and liquids, the filling operation (F) is done interruptedly in a first step (P1) at a fill opening (44). A press element (36) executes a plurality of pressings up to a constant stroke position (HS). Not until a second method step (P2) is the filling operation (F) interrupted, as soon as the pressing pressure exceeds a limit value (PS), whereupon the pressings are continued with shortened strokes. The method offers automatic adaptation of the prefilling time to the pressability of the materials. It thus becomes possible to prefill highly differently pressable material automatically and without specifying a command value in such a way that an optimal performance is attained in terms of the yield and the juice extraction output of a filter press.

Description

The invention relates to a method for feeding Press material to a filter press with a press room for the Solid-liquid separation of material to be pressed, the material to be pressed to Press room fed and there under the influence of a Pressed press force is pressed out.

In such discontinuous filter presses is under Exposure to a pressing pressure the liquid portion of the Pressed material is discharged to the outside via a filter. Doing so the pressing pressure directly via a rigid pressure plate or pneumatically or hydraulically via a flexible membrane the pressed material applied. At the beginning of the feed supply the question arises, how much in the press room must be pre-filled so that a first impression there is sufficient press cushion. It should be noted, that with the pressure plate or membrane in front of it Relationship between effective filter area and current one Bale volume is greater than when withdrawn Pressing element.

The press is overcrowded if it is too big Press cushion the relationship between effective Filter area and current baling chamber volume is too small and thus a deterioration in juicing performance entry. In known pressing processes, the feed was of the pressed material so that during a due constant prefilling time chosen from empirical values is filled. Experience teaches that as a pre-fill time only a fraction of the time for goods that are difficult to press is needed, which applies to goods that can be easily pressed. It turns out to be very useful, especially when pressing fruit difficult to determine an optimal pre-fill time because the Goods can also be pressed from batch to batch fluctuates very strongly.

The invention is therefore based on the object Process for feeding pressed material to a Filter press to indicate which is an optimal performance and Yield of the solid-liquid separation results.

According to the invention, this object is achieved achieved that in a first step the material to be pressed is fed to the press room without interruption, whereby several at the same time by means of press strokes of the press element Impressions are made and that in a second Step the impressions are continued, taking the Feeding the pressed material to the press room during the Pressing is interrupted.

Advantageous embodiments of the method are Find patent claims.

Fig. 1 einen Schnitt durch eine pneumatisch angetriebene Presse bekannter Art,

Fig. 2 einen Schnitt durch eine Kammerfilterpresse bekannter Art,

Fig. 3 einen Schnitt durch eine Filterpresse mit Presskolben nebst einer graphischen Darstellung des zeitlichen Verlaufes von Kolbenhüben, Pressdruck und Zuführung des Pressgutes, und

Fig. 4 ein Flussdiagramm für einen ersten Schritt des erfindungsgemässen Füllverfahrens.

Embodiments of the invention are explained in more detail in the following description and the figures of the drawing. Show it:

1 shows a section through a pneumatically driven press of known type,

2 shows a section through a chamber filter press of a known type,

3 shows a section through a filter press with a plunger in addition to a graphical representation of the course over time of piston strokes, press pressure and supply of the material to be pressed, and

4 shows a flow chart for a first step of the filling method according to the invention.

A pneumatically driven press of known type for Carrying out the method according to the invention shows Fig. 1. It comprises an elongated cylindrical Press tank 1, in the middle of which a flexible inside Membrane 2 is attached. The membrane 2 divides the Press tank 1 lengthways into a pressure chamber 3 and a press room 6. The pressure chamber 3 is connected by a double arrow 4 symbolized opening compressed air supplied or discharged. The too Pressed goods are the press room 6 through an opening 5th fed. Under the influence of the compressed air in the pressure chamber 3 on the membrane 2, the liquid portion of the Press material through a filter 7 in the press tank 1 into one Collecting channel 8, from where it goes to the outside via a line 9 is derived. To carry out the inventive In a first step, the supply of the pressed material is Press material without interruption in the press room 6 via the Opening 5 supplied, the membrane 2 by means of press strokes several impressions can be made simultaneously.

Fig. 2 shows a chamber filter press of a known type in Cut. Above the chamber floor 10 as a carrier is in one Distance mounted a filter 11, which by a Intermediate frame 12 spaced and through a chamber cover 14 as a support fixes a pressure membrane 13 opposite stands. The material to be pressed is fed in via a Opening 15 in the intermediate frame 12 continuously, under the effect of an opening 16 in the chamber lid 14 or discharged compressed air by means of press strokes Pressure membrane 13 simultaneously several impressions be made. The liquid portion squeezed out the material to be pressed is opened through an opening 26 in the chamber bottom 10 derived to the outside. The unit of the so far described Chamber filter press is activated from the outside Clamping forces held together by the arrows 17th are symbolized. For an emptying process of the Press residue is between the chamber floor 10 and Intermediate frame 12 at the point designated by 18 Removal of the clamping forces 17 made a separation.

Fig. 3 shows schematically a horizontal Filter piston press of known type. It comprises one Press jacket 31, which is detachable with a pressure plate 32 connected is. The pressure plate 32 is opposite inside the press cover 31, the second pressure plate 33, which via a plunger 36 on a piston rod 43 is attached. The piston rod 43 is in one hydraulic cylinder movably mounted, as the arrow 20 indicates, and leads over the plunger 36 Pressing operations. Between the pressure plates 32 and 33 the pressed material 37 via a closable filling opening 44 introduced through which a variety of Drainage elements 35 extends.

The drainage elements 35 guide the during the pressing process liquid phase of the pressed material 37 in collecting chambers 38 and 39, which is arranged behind the pressure plates 32 and 33 are. The pressed material can be fruit and at the liquid phase around fruit juice. Under the Pressure action of the plunger 36 reaches the liquid phase from the pressed material 37 via the collecting chambers 38, 39 in Drain lines 40 to the outside. The press force is in the generated hydraulic cylinder, being between the front Pressure plate 32 together with the press jacket 31 and the cylinder there is a non-positive connection, not shown. After the pressing process is complete, the Press by loosening and axially moving the press jacket 31 from the pressure plate 32.

The known procedure of pressing is in Usually the following:

Filling process:

• The press jacket 31 is with the pressure plate 32nd closed,
• The plunger 36 is withdrawn,
• The material to be pressed 37 is filled in via the opening 44.

Pressing process:

• The whole press unit shown in Fig. 3 is around the Center axis rotates,
• The plunger 36 is advanced under pressure,
• The juice is separated from the pressed material by pressing,
• The pressure is turned off.

Loosening process:

• The plunger 36 is rotated all over Fig. 3 retracted press unit, the leftover pressed material loosened up and torn open becomes.

Another pressing process:

• The process steps of pressing and loosening are called Repetitions per batch of pressed material are repeated several times until a desired final squeezing condition has been reached.

Emptying process:

• The press residues are opened by opening the press jacket 31 emptied from the pressure plate 32.

The procedure according to the invention for a Filter piston press is closer with reference to FIG. 3 described. There are next to the scheme already described graphic representations associated with the filter piston press shown which for the two inventive steps P1 and P2 the piston strokes between positions HM and HS, the corresponding pressure profile with limit PS and show the filling function F over time t. How through that Time diagrams next to the press jacket 31 is shown at the beginning by pressing the "Start Fill" command 37 continuously by means of a pump via the opening 44 Press room fed. The pressure plate 33, starting from a position HM in the direction of arrow 20 moved towards the opening 44 and when the Position HS immediately back to its starting position HM withdrawn.

During the first step labeled P1 this process is repeated until the forerunner Pressure plate 33 in the filled goods 37 the pressing pressure increases to a predetermined value PS, as is the time diagram for the press pressure shows. An identified by F. Bar shows the continuous running at the same time Filling process.

If the target pressure PS is reached, the pre-filling and so that the step P1 of the filling process ends. After this The point in time is in a second step labeled P2 only filled in discontinuous phases, which each start with the retraction of the pressure plate 33. Like in Diagram not recognizable, you can expediently by Withdrawal of the pressure plate 33 in the press room a negative pressure generate which is cleaning on the drainage elements 35 filter acts. The position corresponds to HS a constant stroke position of the pressure plate 33 and thus reduced to a constant value Press volume. This has the advantage of being repeated at the stroke position HS reached according to the invention for the Pressing process favorable ratio between the filter area of the Drainage elements 35 and amount of the pressed material 37 is in the press.

In a variant of the The method is based on the ancestor of the printing plate 33 the constant position HS is waived. That's what you drive for in the first step P1, only with each pressing, until the pressure in the material to be pressed is below or equal to Feed pressure of the material to be pressed reached during filling process F. The pressure plate 33 reaches with progressive Filling of the press room Positions that differ from HS remove more and more. The continuous filling process F is interrupted in this case if a Limit position HE is reached, with which the second Method step P2 begins.

In a further variant of the method, it can be in the With regard to the pressability of the pressed material as prove beneficial in the course of the first step Reaching the limit for the press stroke or press pressure to reduce the force applied to the pressing element until the pressing pressure to a value below the supply pressure of the Pressed goods reduced. The value is kept at this Press pressure then over a predetermined period of time approximately constant before the initiation of the withdrawal of the Press element takes place.

FIG. 4 shows a summary of that of FIG. 3 described delivery method a flowchart for the first step P1. With the impressions with the Press strokes of the pressure plate 33 to the constant position HS becomes the loop "pressure plate before" - "target stroke HS reached? "-" Target pressure PS reached? "or" Pressure plate back "-" pressure plate behind? "-" pressure plate forward " run through. If the target pressure PS is reached, the Command "Stop fill" and "End step 1".

The procedure described so far for feeding Offers material to be pressed with the two steps according to the invention an automatic adjustment of the pre-fill time to the Pressability of the goods. The first step is just straight filled in as much material as is required to make one to generate sufficient press cushion. At the same time avoid overfilling the press. So that will enables goods to be pressed very differently automatically and without specifying the setpoint so that in relation to the yield and juicing performance of a filter press optimal behavior is achieved.

Claims (8)

1. Process for feeding material to be pressed (37) to a filter press having a pressing chamber (6) for the solid-liquid separation of material to be pressed the material to be pressed being fed to the pressing chamber (6) where it is pressed by a pressure-operated pressing element (2, 13, 33), characterised in that, in a first step (P1), the material to be pressed (37) is fed continuously to the pressing chamber (6), a plurality of pressing operations being carried out simultaneously by means of pressing strokes of the pressing element (2, 13, 33) and that, in a second step (P2), the pressing operations are continued the feed of the material to be pressed (37) to the pressing chamber (6) being interrupted during the pressing operations.
2. Process according to claim 1, characterised in that the second step (P2) is begun by interrupting the feed of the material to be pressed (37) to the pressing chamber (6) as soon as a predetermined pressure limit (PS) has been reached in the pressing chamber during a pressing operation.
3. Process according to claim 1, characterised in that, in the first step (P1), the feed strokes of the pressing element (2, 13, 33) during the pressing operations are such that the pressure in the material to be pressed (37) increases only to a limit situated below the feed pressure for the material to be pressed (37) and that a negative pressure is produced in the pressing chamber after the return strokes of the pressing element (2, 13, 33).
4. Process according to claim 3, characterised in that the second step (P2) is begun by interrupting the feed of the material to be pressed (37) to the pressing chamber (6) as soon as the pressing element (2, 13, 33) has reached a predetermined minimum pressing stroke (HE) in the pressing chamber (6) in a pressing operation.
5. Process according to claim 1, characterised in that, in the second step (P2), the feed of the material to be pressed (37) to the pressing chamber (6) is interrupted when the pressure in the pressing chamber increases.
6. Process according to claim 1, characterised in that, in the first step (P1), the feed strokes of the pressing element (2, 13, 33) during the pressing operations are such that the volume of the pressing chamber is reduced only to a limit (HS) and that the return of the pressing element is initiated once the limit (HS) has been reached.
7. Process according to claim 6, characterised in that when the filter press is a piston press, an inquiry for a nominal value of the piston stroke determines when the limit (HS) of the pressing chamber volume has been reached.
8. Process according to one of claims 3 or 6, characterised in that, in the first step, once the limit of the pressing chamber volume (HS) or pressure has been reached, the pressure directed towards the pressing element (2, 13, 33) is reduced until the pressure falls below the feed pressure for the material to be pressed (37) and that this pressure is then kept almost constant for a specific period of time before the return of the pressing element is initiated.

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